This application is based upon and claims the benefit of priority from prior Japanese Patent Application P2001-286754 filed on Sep. 20, 2001; the entire contents of which are incorporated by reference herein.
The present invention relates to a method for filling a trench that is formed in a production process of a semiconductor device. Particularly, the present invention relates to a method for filling the trench with a high aspect ratio by using a high density plasma (HDP) technique. Further, the present invention relates to the Shallow Trench Isolation (STI) technique with a high isolation resistance.
The minute isolation is required in the manufacturing of semiconductor devices, along with the shrink of the semiconductor device in recent years. STI has been used. And, the shrink of STI area is also being carried out for the same purpose. The width of the opening of the STI trench becomes narrow and the depth of it becomes deep. That is, the aspect ratio that is the ratio of the depth to the width of the opening increases. Thus, the process filling an insulator into the trench with high aspect ratio is needed in forming the STI area.
The silicon oxide (SiO2) film by HDP chemical vapor deposition (C V D) (hereinafter, this silicon oxide film is called an HDP film) is filled into the high aspect trench. However, the aspect ratio of the trench of STI area increases with the further shrink of the semiconductor device in recent years. A trench exceeding a high aspect ratio of 3 is not able to fill even by the HDP film. When the HDP film is filled into the trench on a silicon substrate, the upper part of the trench is closed with the HDP film. A void results within a trench. The trench cannot completely fill.
Also, the STI area, whose width is narrow and isolation performance is high, is required in the device that uses the high voltage such as EEPROM (electrically erasable programmable read only memory). The STI area, whose width is narrow and isolation performance is high, has a deep trench. The aspect ratio of the trench becomes very high in the STI area of the cell array of the EEPROM. The filling of the HDP film into the deep trench was difficult.
A manufacturing method of a semiconductor device according to embodiments of the present invention includes forming a trench on a surface of a semiconductor substrate, oxidizing thermally a side face and a bottom face what is called internal surface of the trench, forming a first silicon oxide film into the trench with an HDP, removing the first silicon oxide film formed on the side face until a part of the side face is exposed, oxidizing thermally the part of the side face exposed, and forming a second silicon oxide film on the first silicon oxide film and on the side face with an HDP.
A manufacturing method of a semiconductor device according to embodiments of the present invention includes forming a trench on a surface of a semiconductor substrate, forming a first silicon oxide film into the trench with an HDP, removing the first silicon oxide film formed on the surface until the surface is exposed, and forming a second silicon oxide film on the first silicon oxide film and on the exposed surface with an HDP.
A manufacturing method of a semiconductor device according to embodiments of the present invention includes forming an insulating film on a semiconductor substrate, forming a polysilicon film on the insulating film, forming a trench penetrating the insulating film and the polysilicon film and dug in the semiconductor substrate, forming a thermal oxide film on an internal surface of the trench by a oxidation of an oxygen radical, and filling a first silicon oxide film into the trench with an HDP.
A manufacturing method of a semiconductor device according to embodiments of the present invention includes forming an insulating film on a semiconductor substrate, forming a polysilicon film on the insulating film, forming a trench penetrating the insulating film and the polysilicon film and dug in the semiconductor substrate, forming a first thermal oxide film and a second thermal oxide film by a thermal oxidation of the semiconductor substrate and the polysilicon film on an internal surface of the trench, forming a first silicon oxide film on the first thermal oxide film and the second thermal oxide film with an HDP, removing the first silicon oxide film formed on an upper part of the second thermal oxide film, and forming a second silicon oxide film on the first silicon oxide film with an HDP.